The present invention relates to a method of linearly braking a carriage, a linear brake apparatus and a chair incorporating the linear brake.
Linear brakes are available which prohibit the movement of a carriage traveling in one direction along a rod, bar, elongated member or surface. In some instances, the device normally prohibits movement and when a control signal, particularly a mechanical control signal, is applied to the brake, the brake releases and allows linear movement with respect to a fixed object. The brake may prohibit movement in only one direction along the object or may prohibit movement in two linear directions along the object.
In a specific example, linear brakes are utilized in chairs or seats on commercial aircraft. Particularly, these chairs rotate or swivel about a vertical central axis, move fore and aft along a pair of longitudinal runners, and move side-to-side or laterally along a pair of lateral runners. Typically, braking mechanisms are utilized for the rotational, longitudinal and lateral movements. On commercial aircraft, it is required that the brakes be normally engaged such that the chair does not swivel, nor move fore and aft (longitudinally), or side-to-side (laterally). When a control signal, which is usually a mechanical signal, is applied to the braking mechanism, the chair is enabled to rotate, to move side-to-side and move back and forth. The present invention relates to linearly braking the longitudinal and lateral movements.
One known linear brake is made by P. L. Porter Company. Generally, this brake is a friction type brake mechanism which travels on a smooth rod extending between various components of the chair immediately beneath the bottom cushion of the chair. U.S. Pat. No. 3,874,480 describes, at least in part, the Porter brake. When the chair is utilized in commercial aircraft, the brake must withstand at least a 9 g force without failure pursuant to the Federal Aviation Administration regulations. However, the Porter brake is a heavy component for use in the aircraft, requires significant initial force to free the friction-like grip of the brake from the lateral or longitudinal runners and is relatively noisy when the brake travels over the smooth bar, that is the braking surface. The initial lateral or longitudinal force required to free the brake from the traveling surface is significant as compared with the present invention. This force is not diminished by the mechanical release control signal applied to the brake to release it from the locked position.